PROJECT SUMMARY/ABSTRACT When children become victims of physical trauma, they often become victims of mental and emotional trauma as well. The mental health sequelae most frequently manifest as post-traumatic stress disorder (PTSD), which can and often does harm the child?s mental and emotional health, social function, and academic performance, and can lead to more serious and persistent sequelae that are more difficult and costlier to treat. Symptoms of PTSD do not appear until weeks after the traumatic experience. Treatments such as collaborative stepped- care and cognitive behavioral therapy are effective, but are markedly easier, more effective, and cost-effective when initiated early. The fundamental problem is that there is no way to accurately and feasibly assess risk in children who are at high risk of subsequent development of PTSD following traumatic injury. We have developed and validated PsySTART (Psychological Simple Triage And Rapid Treatment)?a tool to predict PTSD in contexts like natural disasters and mass shootings. PsySTART has been successfully deployed almost exclusively in adults to successfully (area under the receiver operating characteristic curve = 0.76) predict high for subsequently developing PTSD. PsySTART evaluates 11 risk factors for PTSD. These risk factors do not rely on acute symptoms of stress, which is ubiquitous and often transitory and may never lead to PTSD. Our preliminary data in a study of 63 children admitted to a pediatric trauma center suggest that PsySTART can also be adapted for use with injured children while still in the ED, and can be unobtrusively administered by ancillary medical personnel without the need to interview the patient. However, while PsySTART measures risk factors that reliably predict PTSD at the population level, we still need to define a cutoff score that distinguishes those who most need close follow-up and treatment from those who do not. This project will establish that cutoff score in a cohort of children presenting with trauma to the ED. We will develop an individual clinical algorithm using PsySTART for pediatric traumatic injury patients presenting to an ED. We propose one AIM: Evaluate the utility of the PsySTART instrument in the pediatric ED trauma setting. We will enroll 200 children at two pediatric trauma centers (Harbor-UCLA and UCSF/Benioff Children?s Hospital [UCSF/BCH]), assess risk of PTSD using PsySTART, then follow-up with patients and their parents one month later to determine presence or absence of PTSD. Predictive models will be constructed using a logistic regression framework. We will test two Hypotheses: 1) PsySTART triage will accurately predict risk of development of PTSD in injured children using an individual clinical algorithm; and 2) PsySTART triage can be feasibly integrated into standardized pediatric trauma center practice at the time of injury, and can be delivered unobtrusively without use of mental health professionals or symptom screeners to perform the assessment. If successful, our intervention could be widely deployed in EDs, and could be the first effective strategy to both accurately differentiate those children at risk for clinical PTSD and to proactively target treatment to them.